1. Field of the Invention
This invention relates to a method for writing and reading by a non-contact system digital signals from a computer onto a memory provided at a storage substrate of cards or other substrates.
2. Description of the Prior Art
Recently, cards containing therein semiconductor integrated circuits, the so-called IC cards or LSI cards, have been used instead of magnetic cards widely used in, for example, banks or the like. For transmitting or receiving data and various information between the IC or LSI cards and a read/write unit, a contact system is usually used.
Such system, however, exposes terminals on the surface of the card, so that dust adheres to the terminal, or the terminal is damaged by contact with a foreign object, thereby causing poor contact at the terminal. Or, there is a defect that the terminal picks up static electricity to cause a fault.
In other words, the soiled or damaged terminal cannot reliably transmit the signals and so presents the danger of hindering the IC cards from normal operation or of causing an error during the transmitting data. Furthermore, impuries attach to the terminal to result in a short circuit between the terminals, whereby proper data transmission may be impossible.
However, regarding a power source, a solar cell using method exemplary of the non-contact system has been proposed and put into practical use.
For the solar cell, it is certain that electric power to be consumed in the IC card is obtainable by the non-contact system, but it is difficult for the present technique to transmit or receive, by non-contact between the IC cards and the read/write unit, the clock and data signals necessary to normally operate electronic circuits at the IC card.